1. Field
Barrier coating compositions, composites prepared therefrom, and quantum dot-polymer composite articles including the same are disclosed.
2. Description of the Related Art
A light emitting particle may be dispersed in a polymer host matrix and may be used in various display devices as a composite. For example, a semiconductor nanocrystal called a quantum dot (QD) is dispersed in a host matrix of a polymer or an inorganic material, and thus may be used as a light conversion layer in a light emitting diode (LED) and the like. Particle size of the quantum dots may be relatively readily adjusted during colloid synthesis, and in addition, the particle sizes may be uniformly controlled. When the quantum dot has a size of less than or equal to about 10 nanometers (nm), a quantum confinement effect becomes significant, and thus, as the particle size decreases, the bandgap increases, and thereby the energy density becomes larger. Accordingly, the quantum dot may emit light in a visible light region with excellent luminous efficiency and thus, active research efforts have been focused on application of the quantum dot to various lighting devices, a light emitting diode (LED) for a backlight unit, and the like.
The quantum dot has theoretical quantum efficiency of about 100% and may emit light with a high color purity (e.g., of less than or equal to about 40 nm of a full width at half maximum (FWHM)). Thus, the quantum dot is expected to provide high luminous efficiency and improved color reproducibility compared to an inorganic phosphor used in a conventional art. However, since the quantum dot is a short-living nano-size particle, which is vulnerable, for example, to an external factor such as moisture or oxygen (unlike the inorganic phosphor, which is a micro-size particle), development of technology for overcoming this problem is needed. When the quantum dot is used in a quantum dot-polymer composite in a light emitting diode or a quantum dot sheet, it is important to well maintain a passivation layer on the surface of the quantum dot in order to secure its high efficiency and color purity. The quantum dot-polymer composite may have a barrier coating for protecting the quantum dot from moisture or oxygen, and as the barrier coating, a deposited metal oxide (e.g., formed by sputtering and the like) has been extensively used. However, a currently-used barrier coating shows an insufficient performance with regard to the economic or technological aspects of the device.
Thus, there remains a need in a new and efficient barrier coating that would be applicable to a quantum dot polymer composite.